Hydrogenation of waxes



Patented Nov. 15, 1966 3,285,845 HYDROGENATION F WAXES Jacques Demeester, Courbevoie, Seine, France, assignor to The British Petroleum Company Limited, London,

found to be suitable in practice. The hydrogen may be used on a once through basis or with recycle.

It is not essential to use pure hydrogen, but if gases rich in hydrogen are used such as catalytic reforming gases, the

England, a British joint-stock corporation 5 flow rate and total pressure should be adjusted to ensure No Drawing. Filed Feb. 5, 1964, Ser. No. 342,801 that the pressure of hydrogen is at least 35 kg./cm.

Claims P y, appliggfion France, Fell 1963, It is found that the conditions of treatment necessary to produce a satisfactory product may vary according to the Clmms' (CL 20827) type of wax which is being treated. Thus for waxes ob- The P Q invention relates t0 the hydrogenation of 10 tained from distillates which have been solvent-treated, the waxes and in particular waxes obtained from petroleum. conditions are generally less severe than for the waxes ob- The term wax is used here to describe b h WaXeS tained from distillates which have not been solvent-treated tained from petroleum distillates and those obtained from or fo waxes btai d f esid es which are generally residues. Such waxes are traditionally treated with sulmicrocrystalline, Increased severity ca be achieved by Phfllric acid and 619136316 acid treatment being intended to 15 one or more of the following factors: increase in temremove from the Wax unstable components Which are perature, increase in hydrogen flow rate and decrease in responsible for its bad odour and its poor colour stability Space el it and the clay treatment being intended to neutralise and Typical conditions of treatment for these two classes of decolorise the wax. waxes are shown in Table No. 1 below:

TABLE 1 Hydrogen Reaction Rate of flow of Ollglll ofWax pressure, tempera- Rate of flow of feedstock hydrogen kgJcrn. ture, C.

Distillate treated with solvent--. 40 250-300 1 vol./vol. of cat./hr vol/vol. of charge. Distillate not treated with solvent 40 300-340 0.5-0.75voL/vo1. cat./hr 40 VOL/vol. of charge.

or residue waxes.

The object of the present invention is to replace these two treatments by a controlled hydrogenation process, thus increasing the yield of refined product and doing away with the necessity of disposing of large quantities of used acid and clay.

According to the present invention, a hydrogenation process consists in bringing the wax into contact at elevated pressure and temperature and in admixture with hydrogen with a catalyst comprising rhenium oxide (ReO on a support.

Preferably 1 to by weight of rhenium oxide is used, based on the weight of total catalyst. Catalysts which are particularly suitable contain from 3 to 10% by weight of rhenium oxide.

If desired the catalyst may also contain one or more iron group metal oxides, particularly nickel oxide. The amount of such oxides may be in the range 1 to 10% wt., particularly 2 to 5% wt. 7

Catalysts of rhenium oxide on a support may be prepared in known manner, particularly by impregnation of the support with a solution of a suitable rhenium salt followed by drying and calcination, preferably at 500 to 600 C. Iron group metal oxides may also be added by impregnation.

The support is preferably a refractory oxide selected from Groups II to V of the Periodic Table, particularly one which has a low activity in itself under the hydrogenation conditions used. The preferred support is alumina. The alumina is preferably calcined before the addition of the oxide or oxides at a temperature of from 500 to 900 C., particularly from 700 to 900 C.

The hydrogenation temperature may be in the range 250 to 340 C. and the pressure of hydrogen at least 35 kg./cm.

The pressure of hydrogen is preferably at least 40 kg./cm. A convenient upper limit is 100 kg./cm. more particularly 70 kg./cm. The space velocity of the wax may be from 0.1 to 5 v./v./hr.

It has been found that it is possible to use low hydrogen treating rates of not more than 80 volumes of hydrogen by volume of wax (equivalent to not more than 450 s.c.f. of hydrogen/barrel of wax) and such rates are preferred. Hydrogen rates of from 10 to 50 vols/vol. have been In the operation of the present invention, the wax in liquid form, is preferably treated, prior to hydrogenation, to deaerate it and remove traces of entrained solvent which could bring about a subsequent deterioration in the Wax. A suitable form of pretreatment is, for example, steam stripping, preferably at temperatures in the range to C. The Wax is then mixed with necessary quantity of hydrogen, the mixture is heated to the desired reaction temperature and then passed over the catalyst at the desired rate of flow and pressure.

Gas is first of all separated from the product at the reaction pressure and the remainder ofthe gas is then separated in a second low-pressure separator. Finally the wax is rectified in steam and subsequently dried in vacuo.

The invention is illustrated by the following examples.

Example 1 The parafiin wax feedstock used had a melting point of 50 C. and came from a non-solvent treated distillate of Kuwait origin.

The process conditions used were Temperature, C. 335 Pressure of hydrogen, l g./cm. 40 Space velocity, v./v./hr. 0.5 Hydrogen addition rate, vol./ vol 40 The catalyst used consisted of 6% wt. of rhenium oxide on an alumina which had been pre-calcined at 800 C. The results obtained are shown in Table 2 below:

The paraffin wax feedstock of Example 1 was treated with a catalyst of 6% wt. rhenium oxide and 3% Wt.

3 nickel oxide on an alumina which had been pre-calcined at 800 C.

The process conditions and results obtained are shown in Table 3 below:

5 TABLE 3 Treating conditions:

Temperature, C 260 280 300 320 340 Pressure of hydrogen, kg./cm. 40 40 40 40 40 Space velocity, v./v./hr v 0. 5 0. 5 0.5 0. 5 Hydrogen addition rate, vol./vol 4O 40 40 40 40 Results obtained:

Saybolt colour before ageing +25 +25 +25 +25 +25 Saybolt colour alter ageing for 1 hr.

at; 200 C 20 +21 +21 +21 +22 Odour 9 10 9 9 9 I claim:

1. A process for improving the odour and colour of wax comprising contacting the wax at elevated temperature and pressure, the temperature being from about 250 to 340 C., and in admixture with hydrogen, the pressure of hydrogen being at least 35 kg./cm. with a catalyst comprising from 1 to 25% by weight of rhenium oxide on a support.

2. A process as claimed in claim 1 wherein the amount of admixed hydrogen is not more than 80 volumes/ volume of wax.

3. A process as claimed in claim 2 wherein the amount of admixed hydrogen is from 10 to 50 vols/volt 4. A process as claimed in claim 1 wherein the hydrogen pressure is from to kg./cm.

5. A process as claimed in claim 1 wherein the wax is derived from a solvent-treated distillate and the hydrogenation temperature is from 250 to 300 C.

6. A process as claimed in claim 1 wherein the wax is derived from a petroleum fraction selected from the class consisting of non-solvent-treated distillates and residues and the hydrogenation temperature is from 300 to 340 C.

7. A process as claimed in claim 1 wherein the catalyst contains from 3 to 10% wt. of rhenium oxide.

8. A process as claimed in claim 1 wherein the catalyst also contains from 1 to 10% wt. of an iron group metal oxide.

9. A process as claimed in claim 8 wherein the iron group metal oxide is nickel oxide.

10. A process as claimed in claim 1 wherein the support is alumina.

References Cited by the Examiner UNITED STATES PATENTS 2,846,356 8/ 1958 Mills et al. 20827 2,915,448 12/1959 Annable et al. 20827 3,119,762 1/1964 Siegmund 20827 3,166,489 1/1965 Mason et al 20827 3,206,387 9/ 1965' Smilski 20820 DANIEL E. WYMAN, Primary Examiner. P. E. KONOPKA, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,285,845 November 15, 1966 Jacques Demeester It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 36, for "(ReO read (Re O Signed and sealed this 12th day of September 1967.

(SEAL) Attest:

ERNEST W. SW'IDER Attesting Offioer EDWARD J. BRENNER Commissioner of Patents 

1. A PROCESS FOR IMPROVING THE ODOUR AND COLOUR OF WAX COMPRISING CONTACTING THE WAX AT ELEVATED TEMPERATURE AND PRESSURE, THE TEMPERATURE BEING FROM ABOUT 250 TO 340*C., AND IN ADMIXTURE WITH HYDROGEN, THE PRESSURE OF HYDROGEN BEING AT LEAST 35 KG./CM2, WITH A CATALYST COMPRISING FROM 1 TO 25% BY WEIGHT OF RHENIUM OXIDE ON A SUPPORT. 